@@lenamv96 havent tried arknights yet, thought about it since i do like tower defense games but i kinda grew distant from mobile games so eh. though i do agree that the video is really good :D!
This is a mashup of various official 3d animations made for different events in the game. There is an anime (with a second season coming soon) that uses 2d animation. I'd recommend checking it out but heads up that the first season isn't as heavy on the action and is more like a prologue with a lot of set up and introduction to the world